Drinkard U.S. Pat. No. 3,496,218 discloses the preparation of nitriles by the reaction of hydrogen cyanide and butadiene in the presence of a nickel catalyst and a boron promoter. Other improvement patents on this technology include Rapoport U.S. Pat. No. 4,330,483 and Barnette et al. U.S. Pat. No. 4,339,395.
When 2-methylglutaronitrile and adiponitrile are manufactured by the above processes, the reaction mixture includes not only these nitrile products, but also organo boron compounds that are difficult to separate from the nitriles by simple distillation. These nitriles are hydrogenated to hexamethylenediamine and 2-methylpentamethylenediamine, and the diamines are used in the manufacture of nylons. The organo boron compounds contained in the nitriles render the hydrogenation catalysts less effective by limiting the catalysts' activity, selectivity, and life.
An object of the present invention is to produce higher quality adiponitrile and 2-methylglutaronitrile, higher yields of diamine upon hydrogenation of the nitriles, and less undesirable by-products such as benzene, which is produced by thermal decomposition of the boron contaminants.